The present invention relates to a method and a system for preparing dental restorations from ceramic or polymeric material to achieve color and opacity gradients that simulate natural dentition.
A molding method such as that described for example in EP 0 231 773 A1 or U.S. Pat. No. 5,702,514 A is known for the preparation of dental restorations from ceramic material. In that method, a model of a dental restoration made of a material that can be burned out completely is fitted onto a strand forming the later casting channel inside a press muffle and the press muffle is filled with an investment material, so that the model is completely surrounded by the investment material. The investment material is cured to form a refractory press mold and the model is burned out, in order to produce the mold cavity corresponding to a dental restoration in the cured press mold. A ceramic material is then forced through the casting channel into the press mold by applying pressure, in order to fill the mold cavity corresponding to the dental restoration and consequently produce the dental restoration from the ceramic material.
A disadvantage of the known methods and systems is that the known molding methods are only suitable for dental restorations of a single color. If a naturally appearing reproduction in the form of a dental restoration of color and opacity gradients that occur in a great variety of natural dentition is desired, then according to the prior art, a subsequent surface treatment, such as for example by painting or coating, is unavoidable. Such a subsequent surface treatment is laborious and expensive because of the manual work involved.
It is therefore an object of the present invention to provide a method and a system for preparing dental restorations from ceramic or polymeric material, wherein color and opacity gradients are achieved without subsequent surface coating.